Wagram said that before humans (Mitra) even walked in the face of the earth Remnants maintained peace and harmony. but how could that be if Remnnants are unbound they'll trigger a Collapse which bring chaos. Maybe there where Guardians that keep them in check. although Remnant monsters doesn't cause a Collapse in fact they can even use other Remnants mainly Remnant Weapons.
It is unknown why Remnants cause a Collapse and able to consume peoples minds. Maybe because that Remnant should be bound to maintain peace and Harmony.
All Remnants are living creatures
Category of Remnants (only my idea)
- Remnant Warden - Possibly the first guardians of the Remnants taking the form of Mitra's or other species
- Remnant Weapon - Remnants that look like Weapons
- Remnant Monster - Remnants that are like living organism (able to use other Remnants)
- Remnant Accessories - Remnant that mostly used for decorations and style (Flachonelle, etc.)
- Others - Remnant that looks different from the rest (Arco Iris, Umbermarici, etc.)
Reason why The Conqueror wants to release them is that People treating Remnants nothing more than beneficial tools. Saying that they will push the Remnants power to beyond there limits and destroy all existence. Which mean that Remnants can also cause a Collapse-like outcome if over used.
Wilfred Hermeien said that we shall all be released stating that Remnants should be Released. The release Remnants will cause a Collapse but instead of spawning monsters it consumes lesser life forms like men which kills them. Although Hermeien was able to synchronized with it and gain tremendous powers but the other Lords did not, maybe because that the Core Remnants refuses to be unbound since they came to this world to help living creatures and Vice Versa (Valeria Heart to protect Athlum, Emeth Tag to protect Royotia,..etc.)
Marshall are a race of beings that is able to control all remnants. Maybe there one of the Guardians of Remnants keeping them in check aside from the Remnant Warden.